Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.

Some epiphytic Hymenophyllaceae are restricted to lower parts of the host (< 60 cm; 10-100 μmol photons m(-2) s(-1)) in a secondary forest of Southern Chile; other species occupy the whole host height (≥ 10 m; max PPFD > 1000 μmol photons m(-2) s(-1)). Our aim was to study the photosynthetic l...

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Main Authors: María José Parra, Karina I Acuña, Angela Sierra-Almeida, Camila Sanfuentes, Alfredo Saldaña, Luis J Corcuera, León A Bravo
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2015-01-01
Series:PLoS ONE
Online Access:https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0145475&type=printable
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author María José Parra
Karina I Acuña
Angela Sierra-Almeida
Camila Sanfuentes
Alfredo Saldaña
Luis J Corcuera
León A Bravo
author_facet María José Parra
Karina I Acuña
Angela Sierra-Almeida
Camila Sanfuentes
Alfredo Saldaña
Luis J Corcuera
León A Bravo
author_sort María José Parra
collection DOAJ
description Some epiphytic Hymenophyllaceae are restricted to lower parts of the host (< 60 cm; 10-100 μmol photons m(-2) s(-1)) in a secondary forest of Southern Chile; other species occupy the whole host height (≥ 10 m; max PPFD > 1000 μmol photons m(-2) s(-1)). Our aim was to study the photosynthetic light responses of two Hymenophyllaceae species in relation to their contrasting distribution. We determined light tolerance of Hymenoglossum cruentum and Hymenophyllum dentatum by measuring gas exchange, PSI and PSII light energy partitioning, NPQ components, and pigment contents. H. dentatum showed lower maximum photosynthesis rates (A max) than H. cruentum, but the former species kept its net rates (An) near Amax across a wide light range. In contrast, in the latter one, An declined at PPFDs > 60 μmol photons m(-2) s(-1). H. cruentum, the shadiest plant, showed higher chlorophyll contents than H. dentatum. Differences in energy partitioning at PSI and PSII were consistent with gas exchange results. H. dentatum exhibited a higher light compensation point of the partitioning of absorbed energy between photochemical Y(PSII) and non-photochemical Y(NPQ) processes. Hence, both species allocated energy mainly toward photochemistry instead of heat dissipation at their light saturation points. Above saturation, H. cruentum had higher heat dissipation than H. dentatum. PSI yield (YPSI) remained higher in H. dentatum than H. cruentum in a wider light range. In both species, the main cause of heat dissipation at PSI was a donor side limitation. An early dynamic photo-inhibition of PSII may have caused an over reduction of the Qa+ pool decreasing the efficiency of electron donation to PSI. In H. dentatum, a slight increase in heat dissipation due to acceptor side limitation of PSI was observed above 300 μmol photons m(-2)s(-1). Differences in photosynthetic responses to light suggest that light tolerance and species plasticity could explain their contrasting vertical distribution.
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publisher Public Library of Science (PLoS)
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spelling doaj-art-145b7a92be604b80af5d8286e0d439722025-08-20T03:10:58ZengPublic Library of Science (PLoS)PLoS ONE1932-62032015-01-011012e014547510.1371/journal.pone.0145475Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.María José ParraKarina I AcuñaAngela Sierra-AlmeidaCamila SanfuentesAlfredo SaldañaLuis J CorcueraLeón A BravoSome epiphytic Hymenophyllaceae are restricted to lower parts of the host (< 60 cm; 10-100 μmol photons m(-2) s(-1)) in a secondary forest of Southern Chile; other species occupy the whole host height (≥ 10 m; max PPFD > 1000 μmol photons m(-2) s(-1)). Our aim was to study the photosynthetic light responses of two Hymenophyllaceae species in relation to their contrasting distribution. We determined light tolerance of Hymenoglossum cruentum and Hymenophyllum dentatum by measuring gas exchange, PSI and PSII light energy partitioning, NPQ components, and pigment contents. H. dentatum showed lower maximum photosynthesis rates (A max) than H. cruentum, but the former species kept its net rates (An) near Amax across a wide light range. In contrast, in the latter one, An declined at PPFDs > 60 μmol photons m(-2) s(-1). H. cruentum, the shadiest plant, showed higher chlorophyll contents than H. dentatum. Differences in energy partitioning at PSI and PSII were consistent with gas exchange results. H. dentatum exhibited a higher light compensation point of the partitioning of absorbed energy between photochemical Y(PSII) and non-photochemical Y(NPQ) processes. Hence, both species allocated energy mainly toward photochemistry instead of heat dissipation at their light saturation points. Above saturation, H. cruentum had higher heat dissipation than H. dentatum. PSI yield (YPSI) remained higher in H. dentatum than H. cruentum in a wider light range. In both species, the main cause of heat dissipation at PSI was a donor side limitation. An early dynamic photo-inhibition of PSII may have caused an over reduction of the Qa+ pool decreasing the efficiency of electron donation to PSI. In H. dentatum, a slight increase in heat dissipation due to acceptor side limitation of PSI was observed above 300 μmol photons m(-2)s(-1). Differences in photosynthetic responses to light suggest that light tolerance and species plasticity could explain their contrasting vertical distribution.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0145475&type=printable
spellingShingle María José Parra
Karina I Acuña
Angela Sierra-Almeida
Camila Sanfuentes
Alfredo Saldaña
Luis J Corcuera
León A Bravo
Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.
PLoS ONE
title Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.
title_full Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.
title_fullStr Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.
title_full_unstemmed Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.
title_short Photosynthetic Light Responses May Explain Vertical Distribution of Hymenophyllaceae Species in a Temperate Rainforest of Southern Chile.
title_sort photosynthetic light responses may explain vertical distribution of hymenophyllaceae species in a temperate rainforest of southern chile
url https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0145475&type=printable
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